How to calculate the theoretical capacity of battery electrode materials

How to calculate the theoretical capacity of battery electrode materials

The theoretical capacity of a battery electrode material can be estimated using the relation: 

xFM

where F is the Faraday constant, x is the number of faradays involved in the reaction, and M is the molar mass of the material.

Hence, according to Eq.1, the theoretical charge or discharge capacity of LiCoO2 can be calculated to be 274 mAh/g, using 1.0, 26.80 Ah/mol, and 97.87 g/mol for x, F and M, respectively.

LiCoO2 Li1xCoO2 + xLi+ + xe  ...............................(1)

Likewise, according to Eq.2, the theoretical charge or discharge capacity of graphite (C) can be calculated to be 372 mAh/g, using 1/6, 26.80 Ah/mol, and 12 g/mol for x, F and M, respectively.

C + xLi+ + xe  LixC .........................................(2)

 

Examples are shown in the table below.

Anode Cathode x/ mol Thoeretical Capacity/ mAh g-1 Attainable Capacity/ mAh g-1
Graphite 1/6 372 350
Li4Ti5O12 3 175 170
Si 3.75 3579 same
LiCoO2 1 274 145
LiNi1/3Co1/3Mn1/3O2 1 278 150
LiFePO4 1 170 160

 

 

 

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